'Durability' is a vague and ambiguous term, allotted diverse definitions from researchers in different fields; to improve understanding of stone durability there must first be a more rigorous and universal definition of the term. This paper will suggest that a systems approach, derived form geomorphological studies and rock weathering research, provides an insightful framework for studies of stone durability. Deterioration of stone is a function of environmental conditions, weathering processes, material properties and alterations in the stone consequent to exposure. Thus, the weathering or decay, system as a whole dictates the rate and nature of stone decay and determines variability over space and time. Conceptual models comprise the basis for functional geomorphic prediction and retrodiction, but methodologies for assessment of durability have not been conducted within the framework of a systems approach. The stone decay system is subsumed within a value-system, where changing perceptions and validation of heritage influence conservation opportunities and strategies. This paper will attempt to integrate current ideas on physical, chemical and biological processes causing stone decay, the weathering forms and products consequent to decay and their spatial and temporal variability, and the philosophy of conservation, production of heritage and placement of 'value' onto material, artifacts.